<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        .left {
            float: left;
            width: 80%;
            background-color: #f6d889;
            height: 2000px;
        }
        .right {
            margin-left: 80%;
            background-color: #511c0f;
            color: white;
            height: 2000px;
        }
    </style>
</head>
<body>
<div class="wrap">
    <div class="left">我是一个自适应宽度的左边输入框，我支持自动换行不会被右边导航栏所覆盖内容。
    </div>
    <div class="right">我是固定右边导航栏
    </div>
</div>
</body>
</html>